Ruthenium(II)–NNN complex catalyzed Oppenauer-type oxidation of secondary alcohols

Highly efficient Oppenauer-type oxidation of secondary alcohols to the corresponding ketones has been realized by means of the ruthenium(II) complex catalysts bearing a 2-(benzoimidazol-2-yl)-6-(3,5-dimethylpyrazol-1-yl)pyridine ligand. The oxidation reaction underwent in the presence of acetone as oxidant under mild conditions, reaching final TOF values up to 3960 h⁻¹. The hemilability of the ligand is attributed to the high catalytic activity of these Ru(II) complexes.     

Shielding failure flashover rate under conditions of complex landscapes in mountainous areas

Based on the field investigation, a new Monte-Carlo method, combined with the improved Electro-geometric model (EGM), which can properly reflect the characteristic of random processes with good precision is developed to calculate the lightning flashover rate of transmission lines. Using this calculation system, this paper studied the influences of different landscapes in mountainous area, such as mountain peak, hollow, slope, ditch, etc., on the shielding failure flashover rates (SFFOR) of transmission lines. The decrease of the shielding effects of ground is the main reason of the SFFOR increase. As the increase of the ditch depth and the tower height, the SFFOR increases significantly. The same phenomenon appears when the slope gradient is larger than 20°. Ditch under lines often is ignored in the previous design. But according to the research result, it will apparently influence the ground shielding effect, and therefore lead to shielding failure flashover. This research is helpful for the design, reconstruction and operation of transmission lines.     

Synthesis,Characterization and Crystal Structure of <Emphasis Type="Italic">N,N</Emphasis>′-di[(<Emphasis Type="Italic">E</Emphasis>)-1-(2-hydoxyphenyl)methylidene]-2,6-naphthalenedicarbohydrazide

Abstract  

A new bishydrazone compound, N,N′-di[(E)-1-(2-hydoxyphenyl)methylidene]-2,6-naphthalenedicarbohydrazide (1), has been prepared by condensation reaction of 2,6-naphthalenedicarbohydrazide with salicylaldehyde in ethanol, and characterized by elemental analysis, FT-IR, ¹H- and ¹³C-NMR, ESI–MS and single-crystal X-ray diffraction analysis. The crystal of 1·2DMF belongs to monoclinic, space group P2(1)/n with a = 10.454(1), b = 7.711(1), c = 18.801(2) ?, β = 93.364(1)°, V = 1512.9(3) ?³, Z = 2, D _c  = 1.314 g cm⁻³, μ = 0.093 mm⁻¹, F(000) = 632, Mr = 598.65, the final R ₁ = 0.0861 and wR ₂ = 0.2279 for 7243 observed reflections with I > 2σ(I). The structural analysis reveals that compound 1·2DMF contains one N,N′-di[(E)-1-(2-hydoxyphenyl)methylidene]-2,6-naphthalenedicarbohydrazide molecule and two N,N-dimethylformamide solvent molecules. A 2D supramolecular structure of 1·2DMF was constructed by multiple intermolecular N–H···O and C–H···O hydrogen bonds.     

Community detection in networks by using multiobjective evolutionary algorithm with decomposition

Community structure is an important property of complex networks. Most optimization-based community detection algorithms employ single optimization criteria. In this study, the community detection is solved as a multiobjective optimization problem by using the multiobjective evolutionary algorithm based on decomposition. The proposed algorithm maximizes the density of internal degrees, and minimizes the density of external degrees simultaneously. It can produce a set of solutions which can represent various divisions to the networks at different hierarchical levels. The number of communities is automatically determined by the non-dominated individuals resulting from our algorithm. Experiments on both synthetic and real-world network datasets verify that our algorithm is highly efficient at discovering quality community structure.     

THE EXCESS HEAT EXPERIMENTS ON COLD FUSION IN TITANIUM LATTICE

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Self-assembly of dialkyltin moieties and mercaptobenzoic acid into macrocyclic complexes with hydrophobic "pseudo-cage" or double-cavity structures: supramolecular infrastructures involving intermolecular C-H...S weak hydrogen bonds and pi-pi interactions

Four novel organotin complexes of two types--[R2Sn(o-SC6H4CO2)]6 (R = Me, 1 x H2O; nBu, 2) and {[R2Sn(m-CO2C6H4S)R2Sn(m-SC6H4CO2)SnR2]O}2 (R = Me, 3; nBu, 4)--have been prepared by treatment of o- or m-mercaptobenzoic acid and the corresponding R2SnCl2 (R = Me, nBu) with sodium ethoxide in ethanol (95%). All the complexes were characterized by elemental analysis, FT-IR and NMR (1H, (3C, 119Sn) spectroscopy, TGA, and X-ray crystallography diffraction analysis. The molecular structure analyses reveal that both 1 and 2 are hexanuclear macrocycles with hydrophobic "pseudo-cage" structures, while 3 and 4 are hexanuclear macrocycles with double-cavity structures. Furthermore, the supramolecular structure analyses show that looser and more intriguing supramolecular infrastructures were also found in complexes 1-4, which exist either as one-dimensional chains of rings or as two-dimensional networks assembled from the organometallic subunits through intermolecular C-H...S weak hydrogen bonds (WHBs) and pi-pi interactions.     

Structural diversity of di and triorganotin complexes with 4-sulfanylbenzoic acid: Supramolecular structures involving intermolecular Sn?O, O-H?O or C-H?X (X = O or S) interactions

Twelve new organotin complexes with 4-sulfanylbenzoic acid of two types: R_nSn[S(C₆H₄COOH)]_4−n (I) (n = 3: R = Me 1, n-Bu 2, Ph 3; PhCH₂4; n = 2: R = Me 5; n-Bu 6, Ph 7, PhCH₂8) and R₃Sn(SC₆H₄COO)SnR₃ · mEtOH (II) (m = 0: R = Me 9, n-Bu 10, PhCH₂12; m = 2: R = Ph 11), along with the 4,4′-bipy adduct of 9, [Me₃Sn(SC₆H₄COO)SnMe₃]₂(4,4-bipy) 13, have been synthesized. The coordination behavior of 4-sulfanylbenzoic acid is monodentate in 1-8 by thiol S atom but not carboxylic oxygen atom. While, in 9-13 it behaves as multidenate by both thiol S atom and carboxylic oxygen atoms. The supramolecular structures of 6, 11 and 13 have been found to consist of 1D molecular chains built up by intermolecular O-H?O, C-H?O or C-H?S hydrogen bonds. The supramolecular aggregation of 7 is 2D network determined by two C-H?O hydrogen bonds. Extended intermolecular C-H?O interactions in the crystal lattice of 9 link the molecules into a 2D network.     

不完全偏好下随机选择问题中的极大元定理

提出了不完全偏好的概念.在不完全偏好意义下获得了随机选择问题中的极大元定理和其它一些定理,统一和推广了许多已知结果.     

仿衣壳结构的巨大中空超分子纳米容器的多组分自组装构筑及其功能

在自然界病毒衣壳及笼状蛋白质大分子结构的启发下,运用V型双齿桥连吡啶配体和具有平面四方构型的Pd²⁺离子的溶液配位自组装,一系列具有M_nL_2n经验分子式的多组分巨大中空“纳米容器”型超分子结构被成功构筑。通过在配体内外引入官能团的策略,可以简单地实现衣壳骨架结构的内外功能化。内功能化后的“纳米容器”具有特殊的高密度相,不仅可以实现对不同类型客体分子的包裹,而且可以作为“纳米反应器”实现尺寸均一可控纳米粒子的原位合成以及小分子的催化转化。外功能化的核壳结构则可以对寡肽、DNA等生物分子具有特定的识别作用。本文对此类“纳米容器”型超分子的设计原理、自组装合成与表征、以及功能化应用等方面进行了综述。